When Longer Is Better

Last year we discussed the possibility and the logic of building smaller, lighter snowmobiles that were better suited for stand-up closed-course racing (“Another Fork in the Road”, October November 2000 SnowTech). This time we’ll take you in the other direction.
We have usually preferred longer track sleds to those with 121” tracks and always thought it was simply due to the longer wheelbase. But there’s more to it.

For as many years as we can remember, 121” has been the standard track length on snowmobiles. Of course, when it comes to additional flotation in deeper snow conditions, longer is better. The 121” track has remained as a “staple” in our diet for over thirty years, but this is about to change.

Most all of us are pretty keen to the need of maintaining a balance between ski aggressiveness (amount of carbide, profile, ski pressure) and traction (number of studs, track profile & length) to keep the vehicle handling in check. Too much ski (not enough track) results in oversteering, while not enough ski (too much track) results in understeering. (Oversteering is when you turn the handlebars and the back end of the sled comes around, while understeering is where you turn the handlebars and the sled continues its forward motion.) So far so good?

Back when 121” was settled upon as the “best” length, sleds had much less suspension travel and sat far lower to the ground. Take an old (something like a ‘89 Polaris Indy 500) and measure the amount of track on the ground – then take a good look at the flat-bottomed metal skis. These older sleds had a larger amount of the 121” track on the ground due to their lower ride height, and this balanced out quite nicely with the flat-bottomed (non-aggressive) skis. Easy-steering flat-cornering was the rule.

Since that time, several significant evolutions have happened to our mainstream sleds. The introduction of the FAST M-10 (quickly followed by the Polaris XTRA-14 and XTRA-12 suspensions) brought long travel suspensions to snowmobiling. Also occurring during the same basic timeline was the introduction, and successive evolution of more aggressive ski profiles and deeper lug tracks.

What happened to our so-well balanced sleds was that the longer travel rear suspensions decreased the amount of track on the ground. At the same time, the aggressiveness of the skis increased, outpacing the difference made by deeper lug tracks. Through all of this, the 121” track length remained intact. The result? Sleds that rode much better, but were balanced differently than before. Add some track length back into the recipe and guess what happens? The balance returns.

Long track mountain sleds get closer to what we’re looking for, but with the mega-tall lugs designed to shovel the snow, mountain tracks were too far on the other end of the spectrum; too aggressive.

We kept thinking about the original Polaris SKS models, the ones with the 133.5” tracks. There was a period of nearly ten years that we didn’t ride a 121” Polaris; only SKS models. Our own research continued to tell us there were a number of Polaris riders who clung to the SKS models with their 1.25” tracks. Every year we would see 121” sleds being stretched longer, and while western riders were building mountain sleds out of them, back on the flatland the conversions were for a different reason.

None of this really made sense for a while. Our late model ZX chassis Ski-Doos were the sleds that really had us scratching our heads. They clearly had the superior trailing arm front suspension geometry, and while they handled with accuracy, they were a handful to hang on to for extended length rides. The skis seemed very aggressive, steering sometimes too quick, back ends too loose. Just as if the wheelbase was too short for what we really wanted.

Then came the ride on the FAST Blades. Not a trailing arm front end, but a modified A-arm design. A very similar reaction – the 121” Blade reacted so very quickly. Great for precision steering, but as soon as we hopped on a 144” Blade, it all came into focus. The “light” really came on.

This became very clear with the Ski-Doo Renegade. The 136” x 1.25” track brings back the lost balance so many riders are looking for. It’s a pretty simple concept, but we really didn’t fully grasp all of this until after riding the Renegade, and then the long track Blade. Sleds that are optimized for quick steering response and accuracy, which may be ideal for race environments or short rides, were less than ideal for riding long distances, even hundreds of miles per day; something we refer to as “enduro” riding.

The Polaris EDGE also helped this one come to light. With its forward-sweeping radius rods, the effective wheelbase of these 121” tracked sleds was lengthened, making for a more forgiving trail sled, but admittedly a steering response that was deemed unacceptable by the racing community.

Where is all of this going? Manufacturers like to have as much “commonality” in their vehicles as possible. It helps keep production costs down, and just plain makes life easier for them. But as the factory calibration teams improve their own riding skills, they tend to tune their own sleds for the way they ride.

For the race environment. For the highest performance.

While this approach makes great race sleds, it does not make the best sleds for the long distance riders. 121” tracked sleds may be quicker reacting for tight race courses, but a longer sled works better in a wider range of conditions; especially on anything other than frozen ground or hardpack.

The 2002 Ski-Doo MX Z Renegade is going to be the machine that really drives this point home this season. Be sure to get on one this year and feel the difference between it and an MX Z. For a large number of riders, this stretched approach is exactly what they’re looking for in terms of their trail sled’s behavior. Ski-Doo is already surprised at how intense the interest is in the Renegade.

FAST knows this too. They’ve already seen an incredible level of interest in their new 136” x 1.25” “Striker” versions of the Blade. Even Redline is onto this. Their “short track” will be a 136”; they don’t even plan on offering a 121” version. We also fully expect to see a “new” EDGE SKS, an SX Viper 136”, and maybe even a longer-than 121” ZR to follow this same logic. (Cat is more likely to pursue the lighter, narrower, more agile, leanable machine better suited for closed-course racing.)

The days of 121” sleds being the “standard” short track length could very well be numbered. Five years from now, 121” could easily be over shadowed as the most popular track length. Maybe even the race sleds will see their standard length going to something like 128”. But as riders better qualify themselves, many will discover that characteristics they don’t like about their 121” sleds are all but gone when they ride the same sled with just a bit longer track. Many who are currently perfectly happy with their 121” sleds will be surprised when they figure out what they’ve been missing. Sales of longer tracks, rail extensions and dovetail kits will also see a sharp increase this year as riders stretch their existing sleds.

The exact length that eventually ends up replacing the 121” track as standard issue may be something other than 136”; but for now, 136” is the length that decent tracks are available in. One project we’d like to experiment on is to take a 136” x 1.25” track machine and install a set of large diameter rear idlers (like the Big Wheel Kit from Tri-City Polaris) combined with a set of 10-tooth drivers up on the drive axle. Do this to a new Ski-Doo Renegade and you could have an ultimate “Cross Country” vehicle. We’re not talking about a race sled for closed course racing, nor would this be the ideal mountain vehicle. We want a machine for riding across the countryside like the vast majority of riders do east of the Missouri River all the way to the Atlantic Ocean.
As with everything else, it is all a trade-off. This could provide some nice gains in track efficiency with the bigger wheels, and would suck up a bit more of the track on the ground. This would, however, eliminate our ability to drop in a 2” deep lug track for a week of western riding.

The easy solution (if you’re planning on installing a 1.25” track any way) is to get a set of rail extensions and a dovetail (tunnel extension) and stretch your sled to a 136”. Many aftermarket vendors have complete kits already developed, ready to go. Do it to a sled that is a year (or two or three or four years) old and it’ll be just like having a new machine. Most late model cross country sleds corner so well to start with that unless you spend the majority of your time on really tight trails, you’ll find this combination to be to your liking. Ride quality, stability, flotation, acceleration. About all you’ll lose is some top end. You’ll add a few pounds, but the result should be worth the exercise.
Market demands will continue to dictate what the industry will build, but as the average age of snowmobilers climbs higher and what these riders want from their sleds changes, so will the packaging they will be delivered in. We’ll see.